With many acres of Kentucky’s corn planted late this spring, the crop may be susceptible to fall armyworm damage.

While the amount of fall armyworms has been low, farmers should be monitoring corn in the whorl stage for fall armyworms, said Ric Bessin, an entomologist with the University of Kentucky Cooperative Extension Service.

Most farmers who late-planted corn used a high percentage of Bt corn to prevent damage form corn borers.

“That was a good decision, if they have a market for it,” Bessin said. “We’ve seen some real benefits particularly in June plantings to using Bt varieties that are resistant to European and Southwestern corn borers.”

Research at the UK Research and Education Center in Princeton has found that June planted corn can have as much as a 40-bushel yield loss due to corn borers, he said.

But using Bt varieties does not mean they have the “silver bullet” for all insect problems with this late planted corn, Bessin said. Some of the newer Bt varieties are also effective against fall armyworms but others only suppress them. So, farmers should continue to monitor their fields for these pests.

This pest does not overwinter in the state and must move in from warmer climates each year. Generally, it arrives too late to have much impact on corn, which it prefers to feed on in the whorl stage. But because of the late planting this year corn may be vulnerable to attack for several more weeks.

The number of fall armyworms in the state has been low for the past few years, and 2003 also appears to be another year with low numbers, he said. But as long as the corn is in the whorl stage farmers need to be watching for this insect.

“This insect, when it does show up, does so in very large numbers and can cause some very serious defoliation in this late planted corn,” he said. “It prefers to lay its eggs on vegetative corn, it doesn’t like to lay its eggs after the corn plant has tasseled.”

Monitoring the fields will allow farmers to see if a problem develops and, if necessary, to apply an insecticide.

“I think farmers may think this field is Bt corn and I don’t have to look after it, and that is true with corn borers, but there is this pest that doesn’t show up very often that could still take advantage of some of those fields,” Bessin said. “I’m hoping it doesn’t, but it’s just one of those things we want to remind people that they need to look out for.”